Give a example from everyday life of an angel that measures 90 degrees

The surface area (sa) of a cube with a as the length of each of its sides is given by the formula . if the surface area is known, how can you rewrite the formula to find its side?

Nine more than four times a number is the same as one less than twice the number. find the number?

Which of the following would be a good name for the function that takes the weight of a box and returns the energy needed to lift it?